Art of making cores for electrical apparatus



M. KuBo, ART 0F MAKING CORES FOR ELECTRICAL APPARATUS.I

APPLICATION FILED OCTn I4. I9I5. I

1,345,786. Patented July 6, 1920.

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f, Y Im/ertor: 4 Masakichi KubO,

His Amomeg.

unirse STATES PATENT orr-Icl-z.

MASAKICI- KUBO, 0F TOKYO, JAPAN, ASSIGNOR TO GENERAL ELIECIRIG` COMPANY, A CORPORATION OF NEW YORK.

ART 0F MAKING CORES FOR 'ELECTRICAL APPARATUS.

Application filed October 14, 1915.

To all whom it may concern Be it known that I, MASAKIGHI KUBO, .a subject of the Japanese Empire, and resident of Tokyo, Japan, have invented certain new and useful Improvements in the Art of Making Cores fer- Electrical Apparatus, of which the following is a specification.

My invention relates to the manufacture of laminated iron cores which form parts of, or the entire magnetic circuits of electrical apparatus of various types. Among the v objects of my inventionjare the reduction of the amount of material wasted in the manufacture of such cores, and the more or less complete elimination of the air gaps at the joints within the core and the consequent reduction of the operating losses ,of such cores. While my invention in its broad aspect is applicable to many types of electrical apparatus, its most immediate application will probably be found in themanufacture of transformers, to which it is particularly applicable; so for the sake of simplicity, I shall mostly confine the following description to transformer practice. Its broader application to other velectrical apparatus will be readily understood therefrom.

The importance and application of my invention will be better understood after a brief consideration of the general construction of transformer cores. Commonly such cores are built up of thin iron or steel laminations, each lamination consisting of a number of parts or sections punched from iron or steel sheets; two or more parts or sections are butted together to form a single lamination comprising, so far as possible, a complete magnetic circuit; a corresponding :numberL of air gaps have heretofore necessarily occurred at the joints where the sections meet each other. The sheets from which the sections. are taken have been obtainable in lengths varying up to a maximum of about 19.0 inches. leretofore it has been common to design the cores and laminations thereof, with a View to getting the greatest number of complete lamination sections from each single sheet of metal, but although a great deal of ingenuity has been exercised toward this end, it has in the most common practice, especially for the smaller sizes of machines, been found impossible to Speccation of Letters Patent.

Serial No. 55,790.

. former cores, the greatest part of this waste cach sheet. In the manufacture of transoceurs at the ends of the sheets; for eX- ainple, 1n manufacturing a certain small s1zed transformer, for about every forty-six complete lamination sections taken from a 120 inch sheet, it is necessary to leave at the two ends of the sheet an amount of material, the areav of which would be sulicient to form the parts of four more sections if it were of the proper shape and which must be thrown away as scrap; or to say it another way about, about eight per cent. vof the material of the sheets is lost (except for its scrap value) due to the impossibility of utilizing the entire length of the sheet. By my invention, substantially all of this eight per cent. of the total material may be saved and even the operating losses due to the joints, which heretofore it has been impossible to avoid, may be minimized.

Now my invention is to be applied in a number of ways. F or example, a number of the sheets from which the lamination sections are to be taken, may be welded to.- gether to form what is hereinafter called a strip,in eiiect an Vextended sheet of a definite or indefinite length, from'which the lamination sections may be taken-to better advantage; though in general probably the sheets will be weldedend to end. The sections may then be punched from the strip as they have been punched before from single sheets, but without the usual waste at the Patented July 6, 1920.

ends of each of the original sheets. The

strip may be fed continuously direct from a welder to a punch press, in which case the pre-ss works on what is an indefinitely long strip and the end waste is substantially'envas the others, and entailno additional operating losses due to open butt joints between their parts. However, instead of welding the sheets of metal into strips, the parts of the sections produced'at the ends of separate sheets mayibe' Welded together after the punchingsare struck out. In fact all the joints ietween parts and sections oflall the laminations may be welded if desired, with the first tive sections, 15,

the' consequent elimination of the air gaps at the oints.

It should be observed that the material at the welds between parts and sections of a lamination for a core for electrical apparatus, should be of but ver little greater thickness than Vthe rest ot' t e lamination; preferably it should be of no greater thickness at all, in order that there may be no waste of space within the confines of the core. Unutilized space here, as it will `be well understood, necessitates additional material, otherwise unnecessary, in other parts ot the completed apparatus, Such ,a weld may be secured by an electrical butt welding process hereinafter described, but my invention obviously is not limited to this particular process.

rIhe accompanying drawing, to which reference is made in the following detailed description, forms a part vof this specification. Figure 1 illustrates a portion 'of astrip of sheets welded end to end; the transformer core lamination sections which may be punched therefrom are indicated. Fig. 2 illustrates another strip made .up of metal sheets otherwise arranged the instance illustrated showing a side and an end edge welded together in order that punchings such as arcuate shapes, which are here indicated, may he taken out. Fig. 3 illustrates a process of welding which may be used in carrying out my invention. Fig. 4 illustrates a completed` lamination and transformer core embodying my invention. Fig.

5 illustrates another method of applyingmy invention. d

rllhe portion ot the strip illustrated in F ig. 1 is made up ot a complete original sheet 10 and portions 11 and 12 of two other sheets. tIhese three sheets are welded end to end at 18 and 141. rl`he pieces or lamination sections to be taken out are indicated. It will be observed that commencing at the weld 13 and reading to the right,

are incomplete (except as they are completed by the inaterial from the sheet 11), parts only of these sections coming from original sheet 10. 'l`he tirst section complete in the original sheet 10 is 16. Likewise at the other end oi' the sheet 10, immediately to the lett ot' the weld 14, it will be observed that after the last complete section 17 is taken out, there is sutticient material Jfor parts 18 only of five more sections. As transformers have heretofore been constructed the lamination sections have been taken from separate sheets llike 10, and it has been necessary to throw away as scrap the five lamination or section parts 15 and the five parts 18. According to my invention, however, a number of sheets are first welded together as at 13 and 14 to produce an indefinitely long strip ot' sheet metal and the sections are taken from the strip rather than from` the separate sheets. rIhe parts'o't sections and laminations' similar to those ot' 15 and 1S are not wasted, for as will be apparent from this ligure, the parts 15 ot' sheet 10 are completed by the supplementary parts at the right-hand end of the sheet 11 and leave the punch press as complete sections oil lamiiiations, and likewise the parts 18 are completed from sheet 12.

In some cases it may be desirable to arrange the sheets in other manners to produce a strip from which the pieces desired may be taken out most advantageously. Fig. 2 illustrates one such other arrangement. In Fig. 2 pieces are desired of such a shape and size that it is impossible to get a complete piece from a single sheet. In this particular case the sheets are welded to each other at right angles as illustrated, and from the strip so produced, the pieces may be taken complete.

In Fig. 3 is illustrated a process by which the sheets may be electrically welded without increasing the thickness of the material at the joints. 'Ihis has heretofore been pointed out as a feature which it is substantially necessary to incorporate in the manufacture of cores for electrical apparatus. It will be understood that only such portions of the welding machine are illustrated as will be necessary to understand the process. The exact form ot' the machine, it will be understood by those skilled in the art, may vary very considerably. The head 30 of the machine carries the disk electrode 3.1 which may rotate within the head 30; the head 3() is movable in a plane perpendicular to the plane ot the drawing and also to and trom the work. Immediately below the electrode 31 is a table-32 carrying thc lower electrode 33 in the form ot a copper bai. 'il`he head 3() (and therethrough the electrode 31) and the lower electrode 33 arc connected to opposite sides ot' a suitable source ol electrical energy. Carriers l-l and 35 support the work. ('lainps 36 and 3T clamp the work to the -table 3Q as and when desired. rli`he welding process is carried out as follows: The end ot' a sheet carried by 'the cai'riers 35 is abutted against thc end of the strip 3H on the bar electrode 33 so that the seam lies justbelow the disk elec,- trode 81. r1"he clamps 3G and BT iirc then lowered and clamp the strip 38 and the sheet to the table 82 in these positions. The head 31) and the electrode 31 are thcn pressed downward on the work at one cnd of thc seam. and as current passes between thc electrodes 31 and 33. the disk 31 is rollcd from one end ot' the seam to the other and vent the sheet and strip from separating at the seam. It will be observed that the welding pressure is exerted on, and the welding current passed through the work at right angles to the juncture. After one weld is completed, the clamps 36 and 37 are released and the lengthened strip 38 pulled to the left until its new end reaches the table 32, when the process is repeated with another sheet. It will also be observed that by this welding process the material at the weld is no thickerthan the material of the original sheets; if anything, it may be a lit- Vpresses for punching out lamination sections are so constructed and arranged that once a sheet of metal is properly placed in position in the machine, and the machine started in operation, the laminations are punched out from that sheet successively with considerable rapidity. However, according to the practice universal prior to my invention. it is necessary to stop the machine at the end of each of the mill sheets, and the operator must place another sheet in the machine before the work may be proceeded with. The time lost is Very considerable, for as before indicated the sheets as received from the mill are fairly short, varying from Aabout fifty (50) inches to one hundred twenty (120) inches. By my invention this loss may be substantially entirely eliminated and a very considerable saving in time and in cost of the laminations secured even though the lamination sections made up of welded parts may not be utilized in the construction of electrical apparatus, because by employing my invention itis unnecessary to introduce each of the original sheets into the punch press separately, each following another automatically and the punch press working substantially continuously on an indefinitely long strip. Obviously when my invention is considered solely from this standpoint, that is saving time and cost in getting out lamination sections. it is'not so material to minimize the thickness of the material at the weld.

In Fig. 4 is illustrated a transformer core embodying my invention, the joints in the top lamination being shown by the dotted lilies. It will be observed that the top lamination is made up of three parts; the inherently complete section 41 and the two parts 42 and 43 of the second section of the lamination. These two parts are welded at 43a, and the two sections may be welded at 44. Of course, not every lamination of this transformer core is necessarily made up of more than two parts, for as will be under stood by reference to Fig. l, only a small portion of all the lamination sections of a given core are likely to ,be made up of two parts. All or a part only of the welds may be made priorto'punching the laminations as has been described heretofore, or after the sections and parts of the laminations have been punched out of separate sheets (that is from sheets not welded together as hereinafter referred to). One method of welding these iparts and sections as the core is being assembled is illustrated in Fig. 5. According to this method the coils of the transformer are first wound up on forms or frames and the lamination sections and parts are inserted singly until the completecore is4 built,

up therein. A table 50 carries the coils 51; the first section of a lamination is laid on the blocks 52. As other sections or parts of this lamination are laid down, they are welded at their contacting ed es to the part or parts already in place. ther lamina tions are built up on the first and succeeding laminations in the same way. This welding is done by the machine shown at the right of the figure, the essential parts of which only are illustrated. This machine comprises a standard 54 which may be moved backward and forward as illustrated in dotted lines at 55. standard 54 may be raised and lowered at will and carries a. lower electrode 57 in the shape of a plate, and a disk electrode 58 which may be rolled along the plate for a distance corresponding to the length of the seam to be welded. Two lamination parts 59 and 60 are laid in place and their edges abutted abovethe plate 57 which is inserted into the core space for that purpose. The electrode 58 is then vrolled along over the seam between the parts 59 and 60 and energy is supplied to the electrodes 57 and 58 by the cables 61. After the weld is completed. the disk electrode 58 is moved from contact with the lamination and the standard 54 moved away from the transformer, removing the plate 57 from the core space and allowing the lamination to drop down into place. The clamps 62 and 63 hold the lamination The head 56 of this parts in place during the welding operabeing the subject of my copending application Serial No. 246,032, filed July 22, 1918, which is a division of this application.v

While I have described the principle of my invention and the best mode I have contemplated for applying this principle, other modifications will occur to those skilled in this art and I aimin the appended claim to cover all modifications Which do not involve a departure from the spirit and lscope thereof. y

What I claim as new and desire to secure by Letters Patent of the United States, is,-

The method of manufacturing core laminations for electrical apparatus Whose dimensional component longitudinally of the stock is a non1nu1tiple of the stocks lon itudinal dimension; which consists in We ding strips of stock together edge to edge, and in successively striking laminations from said stock in continuous advance transverse to the Welded edge.

In Witness whereof I have hereunto set my hand this fteenth day of September, 1915.

MASAKICHI KUBO,

Witnesses GrUs BINDER, GEORGE KURIBARA. 

